I've never seen it before. I does look pretty interesting though.

It looks similar to the Soviet B4 Howitzer which was up through WWII.  On the B4, the tracks were permanant.

Trumpeter recently released a kit of it.

Looks a lot like a Russian gun used in WW2 http://en.wikipedia.org/wiki/203_mm_howitzer_M1931_(B-4) but not exactly the same. Your pic seems to have a larger chassis and different recoil mechanism (two tubes on top) and breech arrangment and may be a related cousin, be interested in seeing what others more familiar with it have to say about it's identity. Where'd you find the pic? The gun itself has more "German" or "French" design characteristics to it at first blush and is definitely a big gun.  

Found it.  Apparently it is a US WWI piece; U.S. Naval 7-inch Track-propelled Gun Mk.2 1918.  There is one on display at Quantico, VA.

And a web page dedicated to it: http://www.landships.freeservers.com/U.S.%20Naval%207-inch%20track-propelled%20gun%20Mk.2%201918.htm

I don't know of any model of it out there.

WWI Era Artillery to Be Restored Posted 7/26/2009 Transportation personnel at Naval Support Facility Dahlgren prepare to off-load a World War I-era tractor-mounted artillery piece, the first gun originally test fired to mark the establishment of Dahlgren as a naval proving ground on Oct. 16, 1918. The 7-inch, 45-caliber gun will be restored by the Naval Surface Warfare Center Dahlgren Division. 

I got this from

MILITARY PHOTOS 2009 Military Photo Index   2008 Military Photo Index   2007 Military Photo Index   2006 Military Photo Index   2005 Military Photo Index WWI Era Artillery to Be Restored Posted 7/26/2009 Transportation personnel at Naval Support Facility Dahlgren prepare to off-load a World War I-era tractor-mounted artillery piece, the first gun originally test fired to mark the establishment of Dahlgren as a naval proving ground on Oct. 16, 1918. The 7-inch, 45-caliber gun will be restored by the Naval Surface Warfare Center Dahlgren Division. 0diggsdigg Send Link to a Friend

He is another link:

http://www.google.com/imgres?imgurl=http://www.murdoconline.net/wordpress/wp-content/uploads/2009/07/ww1-cannon.jpg&imgrefurl=http://www.murdoconline.net/archives/8156.html&usg=__NkMmXil2HxFzVkxxqiR01edemJs=&h=1352&w=2000&sz=395&hl=en&start=2&um=1&itbs=1&tbnid=IqA2HfdDYHyCgM:&tbnh=101&tbnw=150&prev=/images%3Fq%3D7-inch,%2B45-caliber%2Bgun%26um%3D1%26hl%3Den%26sa%3DN%26rls%3Dcom.microsoft:en-us:IE-ContextMenu%26tbs%3Disch:1

Wow, thanks a lot!  That was a very quick response with an accurate answer! 

The 7" gun has a very cool history, doesn't it.  I wonder how much (if any) actual action these pieces saw?  The article says they were never delivered before the armistice, so probably none.  It would be a great looking kit, but if it has no combat history, I doubt one would be made for it.  It will be a historical footnote, and little more.  There are alot of cool things that will never be kits, shame that!

Chris

Yep...that looks like it.....two recoil cylinders on the top.....I have not done much with pre WWII artillery but I would assume these did not see much action.....like the T92 of WWII which never made it out of Aberdeen

Rounds Complete!!

Beautiful lines on that barrel. These were secondary armament on Connecticut Class battleships.

EDIT: oops sorry, you said that!

OK...here is the skinny

http://militarypower.wikidot.com/usmc-7-inch-naval-gun-mk-2

They were ready to be shipped when the war ended.....used as coast/home defense in WWII......then all were lost until they found this one!!

Rounds Complete!!